Modern large aircraft, such as the Boeing 777, are typically assembled on a moving assembly line. Moving line assembly requires that the aircraft's main landing gear (MLG), each of which may weigh more 14,000 lbs., be installed while the weight of the aircraft is supported on jacks, with the belly of its fuselage disposed 106 inches or more above the floor. Moreover, repairs or maintenance of large aircraft in the field often must be effected in an actual “flight line” environment, necessitating the removal and installation of large MLG at heights of up to 154 inches above the tarmac, and additionally, in a potentially more hazardous environment, e.g., an Underwriters Laboratories (“UL”) “Class 1, Division 1” (fueled aircraft) environment.
The prior art methods for installing large MLG are typically accomplished on the flight line or in a customer's hangar. Several examples of specialized apparatus adapted for effecting such heavy equipment lifts and manipulations can be found in the patent art, e.g., in U.S. Pat. Nos. 5,460,474 to L. E. Iles; 6,390,762 to W J. Peery et al.; and, 6,485,247 to O. J. Groves et al.
One such prior art method and associated apparatus are those developed for loading the MLG of the Boeing 747 aircraft. However, it should be noted that the 747 MLG loader is not capable of supporting the increased weight of the larger MLG of more recent aircraft, e.g., the Boeing 777, and is therefore incapable of installing the 777 MLG in either a moving line or a flight line environment. This prior art MLG loader comprises three separate towers having associated floor plates that are installed concentrically to the MLG. The equipment necessitates that all six MLG wheels be removed from their respective axels, and that at least three protective sleeves be installed on the bare axels, two on the outboard side and one at the opposite inboard side on the center axle. The protective sleeves are in turn attached to three, six-ton lever chain hoists located on respective ones of the three towers. The lever chain hoists are attached to the plates and respective hoist chains are attached between the tower and the MLG, each of which are then independently tensioned or relaxed in the desired direction to align the upper end of the strut of the MLG into position with and inside of the wheel well of the aircraft.
The foregoing sequence must be accomplished prior to either the installation or the removal of a MLG from an aircraft, and in either case, the aircraft must first be fully supported on jacks, scaffolds or other supports. The disadvantage of the prior art method and apparatus is that they take substantial setup time and manual labor, including disassembly of the MLG wheels and the manual manipulation of the MLG with multiple, independent lever chain hoists, and with the subsequent need to reassemble three of the six wheels on the gear and disassemble the equipment after the MLG has been installed.
Accordingly, there is a long-felt but as yet unsatisfied need in the industry for a loader that can install a large MLG into or remove it from an aircraft in either a moving line or a flight line environment in a controllable, safe, accurate, reliable manner, and in a substantially reduced amount of time.